For two decades pin cylinder screw extruders are known in the rubber and plastic industry (DE 31 50 719) in order to be able to plasticize and disintegrate better and more rapidly materials which are difficult to process. In-the course of the these decades, screw extruders have been ever more improved. Stationary inserted pins have a form which prevents pin breakage. Pin breakage warning devices (DE 32 21 472) and forewarning devices (DE 3 502 437) which respond to the elastic bending of the pins have been developed. In order to avoid the need of individually disassembling the pins when the extruder is to be cleaned and the screw is to be removed from the extruder, hydraulic (DE 35 03 911) and mechanical (DE 35 06 424) drives have been developed with which the pins can be shifted out of their working positions and into withdrawn positions. Through the introduction of additional per se known working means, as for example torpedo pieces inserted in the screw, shearing parts and through grooves cut in the cylinder, further improvement of the plasticizing of the extrudant is attained.
It is an old problem in the extruder technique to find optimal working conditions for the discharge rate, the discharge temperature, the degree of plastification and the discharge pressure. If a good degree of plastification for a certain desired discharge quantity per unit time has been found, and also the temperature of the extrudate has been brought to a value which is favorable for further working of the extrudate, these favorable values cannot be retained when, for example, the rate of rotation of the extruder screw is altered in order further to improve the degree of plastification. Also the discharge quantity per unit time cannot be altered without also altering the degree of plastification and the temperature of the extruded material. This has the result that with a favorable adjustment of the extruder, optimal adjustment of the following machines in the production line cannot be obtained, because, for example, the extrusion temperature is too high or the extrusion quantity per unit time cannot attain the desired optimum value.